Optimizing power consumption in a communication system

ABSTRACT

Within a communication system that includes multiple communication channels, a low-power mode of operation and a higher-power mode of operation are provided. Each channel is allocated to one of several groups, based on criteria such as whether power is allocated to that channel in low power mode, and whether power was allocated to that channel in a previous high power mode. Initial power levels for each channel for each mode are approximated using an interpolation rule known to both the receive and the transmitter. The system switches between modes according to a PMD pre-defined schedule. When a new power mode begins, the receiver measures signal power received on each channel and then transmits corrective information sufficient to allow adaptation of power levels to achieve PMD pre-defined levels of received power.

PRIORITY CLAIM

This application claims priority to European Patent Application No. 12193 867.4, filed on 22 Nov. 2012, the content of said Europeanapplication incorporated herein by reference in its entirety.

TECHNICAL FIELD

Existing DSL lines use DMT tones for communication. Such lines includeat least two modes of operation, of which is a low-power mode. Even inlow-power mode, most of the carriers of DMT tones in DSL lines remainactive, primarily for the purpose of monitoring noise on thecommunication lines. Noise is monitored so that when the DMT carrierswitches from low-power mode to a higher-power mode, the switch canoccur very quickly at power levels for the sufficient to overcome thenoise on the communication lines. The current system is less thanoptimal, in that many DMT carriers are active in low-power mode, even ifthey are not transmitting data. If DMT carriers could be turned off inlow-power mode, substantial energy saving could be achieved.

Another problem in existing DSL systems is that power levels, orinformation rates, or both, change at such rates of speed that receiversand transmitters do not have sufficient time to communicate full datatables for all DMT carriers for every change. As a result, in existingsystems, receivers and transmitters store large data tables which allowthem to complete changes at the rate required. This implementation incurrent systems is deficient, in that these large data tables requirespace and energy to store at both the receivers and the transmitters.One solution might be to reduce in size the data tables, and insteadsend more data between receivers and transmitters before a change ismade. However, such a solution would require significant quantities ofpower, and even then the rate of change would be limited by the maximumspeeds of communication possible between the receivers and thetransmitters. If it were possible to reduce the amount of data that mustbe either stored or transmitted in order to effect changes, benefitscould be in memory space saved, or in power consumed, or in both memoryspace and power consumption.

SUMMARY

In a first aspect the invention encompasses a method for communicatingwithin a communication system that includes a plurality of communicationchannels operable to communicate bits of information in a high powermode of operation and operable to communicate bits of information in alow power mode of operation. The method comprises, for the low powermode of operation, selectively allocating power to a channel in theplurality of communication channels based on channel use during the highpower mode of operation of the respective channel. At least one effectof the invention in the first aspect is to enable an efficient and morewidely used power save mode. For example, should only a relatively smallamount of data need to be transmitted per time unit, rather thanconventionally powering all channels, a selected number of channels maybe powered to enable transmission at low power as required to load asmall number of bits on the respectively selected channel. Inparticular, the channels may be powered just enough to load a minimumnumber of bits on the respectively selected channel.

In an embodiment according to the invention in the first aspectselectively allocating power comprises, if in the high power mode ofoperation the respective channel does not communicate any bits ofinformation, determining not to communicate any bits of information inthe low power mode. At least one effect is that channels that wouldrequire a lot of power to load even a small number of bits can bedisregarded for transmission; in turn only those channels that allowtransmission of bits at relatively low power can be used.

In an embodiment according to the invention in the first aspectselectively allocating power comprises determining to enable measurementof a signal-to-noise ratio (SNR) in the low power mode. At least oneeffect is that SNR measurement results can be obtained and processedduring low power mode on channels that are hardly or not at all used fordata transmission. Thus, when going back to a high power mode, inparticular when going back to an operation at full power, controlparameters, in particular, physical media dependent (PMD) parameters canswiftly be determined to control the respective channel. In anembodiment the measurement is continuous throughout low power mode. Inone embodiment according to the invention in the first aspect themeasurement in low power mode is intermittent. At least one effect is tofurther save power in comparison with measuring SNR continuously. In anembodiment the measurement is cyclically intermittent. At least oneeffect is to enable co-ordination of measurement on a set of channels inthe plurality of channels. In an embodiment at least two respectivechannels determined to enable intermittent measurement of thesignal-to-noise ratio in the low power mode form a group, and whereinpower allocated to channels in the group is allocated to one channel inthe group at a time. The channels in a group can be, but do notnecessarily need to be adjacent in terms of frequency.

In an embodiment according to the invention in the first aspectmeasurement of a signal-to-noise ratio comprises performing an Fouriertransformation. Further, the number of frequencies used in the Fouriertransformation varies with a maximum frequency used for thesignal-to-noise ratio measurement in the plurality of communicationchannels. At least one effect is that processing power and time are keptlow since some frequencies that do not contribute to transmission aredisregarded in the Fourier transformation. In an embodiment the numberof frequencies used in the Fourier transformation varies proportionallyto the maximum frequency used for the signal-to-noise ratio measurementin the plurality of communication channels.

An embodiment according to the invention in the first aspect comprises,if in the high power mode of operation the respective channelcommunicates bits of information, determining to enable communication ofat least one bit of information in the low power mode of operation perpredetermined unit of time. At least one effect is that informationabout channel quality readily available in high power mode can be“reused” in low power. Such information, for example, can be that achannel used for transmission in the high power mode of operation ispreferable over a channel not used for transmission in the high powermode of operation. In the example, this information can be interpretedto provide an indication for use of the respective channel fortransmission also to be preferable in the low power mode of operationover another channel not used for transmission in the high power mode ofoperation.

In an embodiment according to the invention in the first aspect thepower allocated in the respective channel during the low power mode ofoperation is commensurate with the determining for the selected channel.At least one effect is that the power is sufficient to achieve thedetermined performance, such as measurement of SNR in the respectivechannel, or loading of a determined number of bits onto the channel perunit time.

In an embodiment according to the invention in the first aspect the highpower mode of operation of the respective channel immediately precedesthe low power mode of operation of the respective channel.

In a second aspect the invention encompasses a computer readable medium.The medium stores software adapted to perform steps of the methodaccording to the invention in the first aspect.

In a third aspect the invention encompasses an apparatus for use in acommunications system having a plurality of communication channelsoperable to communicate bits of information in a high power mode ofoperation and operable to communicate bits of information in a low powermode of operation. The apparatus is adapted to perform steps of themethod according to the invention in the first aspect.

In a fourth aspect the invention encompasses a communications systemhaving at least one apparatus according to the invention in the thirdaspect. In an embodiment the system is adapted to perform steps of themethod according to the invention in the first aspect.

Below, the invention is described in further exemplary aspects andfurther exemplary embodiments according to the invention are described.In one embodiment, DMT channels are allocated among different groups,based upon whether each such channel transmits information during lowpower mode, and whether each such channel transmitted information in aprior high power mode. Herein, “high power mode” refers to at least onemode of operation with more power than provided in the low power mode.Based on such allocations, some DMT channels may be turned offcompletely turning low-power mode, thereby saving power.

In an alternative embodiment, two or more power scenarios are definedwithin low-power mode, in which specific channels may be turned on inone such scenario to monitor noise level, and such channels may then beturned off in other scenarios in order to converse power.

Many of the embodiments are applicable to multiple communicationsystems, provided that each such system combines multiple channelswithin the system. Therefore, various embodiments may apply to DSLsystems, which combine together DMT carriers. Various embodiments mayalso apply to trunked land-mobile or trunked satellite radio systems,which combine multiple radio channels. Various embodiments may alsoapply to dense wavelength division multiplexing (“DWDM”) or otheroptical communication systems, which combine multiple channels. In anyof the systems noted herein, the various channels may be tied togetherwith a physical binder, as in DSL systems and optical systems, orlogically, as with trunked or satellite radio.

One embodiment is a method for communicating within a communicationsystem that includes multiple communication channels, a low-power modeof operation, and at least one higher-power mode of operation. In suchan embodiment, a communication channel, such as, for example, a DMTcarrier or a DWDM channel, will be allocated to either of two groups.Group A is channels which do not communicate bits of information inlow-power mode and which did not communicate bits of information in theprevious higher-power mode of operation. Group B is channels which donot communicate bits in low-power mode and which did communicate bits ofinformation in the previous high power mode. In such an embodiment,during low-power mode, power is not allocated to channels in Group A,but sufficient power is allocated to each channel in Group B so that aresulting SNR for each channel shall be sufficient for the system tomonitor the noise in that channel. In such an embodiment, all stepsstated above are implemented in an implementation unit, which may belocated on either the server-side of the communication system, or on theclient-side of the communication system.

One embodiment is a method for communicating within a communicationsystem that includes multiple communication channels, a low-power modeof operation, and at least one high power mode of operation. In such anembodiment, a communication channel, such as, for example, a DMT carrieror a DWDM channel, will be allocated to either of two groups. Group A ischannels which do not communicate bits of information in low-power modeand which did not communicate bits of information in the high power modeof operation. Group C is channels which communicate bits in low-powermode. In such an embodiment, during low-power mode, power is notallocated to channels in Group A, but sufficient power is allocated toeach channel in Group C so that resulting SNR shall be sufficient forthe system to load at least one bit per time slot onto that channel. Insuch an embodiment, all steps stated above are implemented in animplementation unit, which may be located on either the server-side ofthe communication system, or on the client-side of the communicationsystem.

In one embodiment, the system stores pre-defined configured values forsome number of channels that is less than the total number of channelsin the system. The system also stores an interpolation rule. The systemmeasures actual values of received power for some of the channels duringa high power mode of operation. Using the margin between actual andconfigured power levels for some of the channels during the high powermode of operation, the interpolation rule will calculate approximatedvalues for the other channels in the system. Such calculations willoccur at both a receiver and a transmitter in the system, so that whenthe system switches from low-power mode to a high power mode,communication between receivers and transmitters will occur at theapproximated power values. Switches from low-power mode to high powermodes and vice versa, are executed at pre-defined PMD times which arestored in the receivers and transmitters. In one embodiment, actualvalues are not stored, the lack of storage reduces the memory storagespace required, and the lack of storage reduces power levels to maintainmemory. In one embodiment, communication of approximated values betweena receiver and a transmitter is not required, thereby reducing transmitpower of communication between the transmitter and the receiver.

One embodiment is a method for communication within a communicationsystem that includes multiple communication channels, a low-power modeof operation, and a high power mode of operation. In this embodiment,PMD control parameters for a high power mode are stored during alow-power mode. In one embodiment, the system stores pre-definedconfigured values for some channels, a pre-defined interpolation rulefor approximating power levels at communication channels in the system,and pre-defined PMD times for switching from one power mode to anotherpower mode. The system uses the configured values and the interpolationrule to determine approximated values of high power mode for channels inthe system. The system stores these approximated values at a memorystorage unit associated with a receiver in the system. In somealternative embodiments, the receiver is located at the client-side, andin other alternative embodiments, the receiver is located at theserver-side.

In an aspect the invention encompasses a method for communicating withina communication system that includes multiple communication channels, alow-power mode of operation, and a high power mode of operation. Themethod comprises—allocating each channel to one of at least two groups.The at least two groups include a group A with channels which do notcommunicate bits of information in low power mode and which did notcommunicate bits of information in a previous full power mode ofoperation, and a group B with channels which do not communicate bits inlow power mode and which did communicate bits of information in theprevious high power mode. The method comprises not allocating any powerto the channels in group A when the system is in low power mode; andallocating sufficient power to each channel in group B when the systemis in low power mode so that a resulting SNR shall be sufficient for thesystem to monitor the noise in that channel. In an embodiment all priorsteps are implemented by an implementation unit that is located ateither the server-side or the client-side. Herein, irrespective of thedirection of transmission being downlink or uplink, the server-side canbe the side of the transmitter and the client-side can be the side ofthe receiver. In an embodiment the high power mode is provided as a fullpower mode.

In an aspect the invention encompasses a method for communicating withincommunication system that includes multiple communication channels, alow-power mode of operation, and a high power mode of operation. Themethod comprises allocating each channel to one of at least two groups,in which group A is channels which do not communicate bits ofinformation in low-power mode and which did not communicate bits ofinformation in a previous high power mode of operation, and group C ischannels which communicate bits of information in low-power mode. Themethod comprises not allocating any power to the channels in group Awhen the system is in low-power triode; and allocating sufficient powerto each channel in group C when the system is in low-power mode so aresulting SNR shall be sufficient for the system to load at least onebit per time slot onto that channel. In an embodiment all prior stepsare implemented by an implementation unit that is located at either theserver-side or the client-side. In an embodiment of the method accordingto the invention the allocating of channels includes an allocating to athird group C of channels which communicate bits of information inlow-power mode; and allocating sufficient power to each channel in groupC when the system is in low-power mode. At least one effect of thisembodiment is that a resulting SNR can be sufficient for the system toload at least one bit per time slot onto that channel during low-powermode. In an embodiment the channels in group B are further allocatedinto subgroups on the basis of a criterion. In an embodiment thecriterion for sub-grouping of channels in group B is the duration oftime of transmission for each channel. In an embodiment the criterionfor sub-grouping of channels in group B is random allocation such thatno channel in group B is correlated with any other channel in group B.In an embodiment the criterion for sub-grouping of channels in group Bis the kind of noise anticipated for each such channel within group B.In an embodiment the noise anticipated for the channels within group Bis either quickly changing noise or slowly changing noise. In anembodiment the noise is quickly changing, and the quickly changing noiseis selected from the group including ham or other amateur radiooperations, police radio operations, and land mobile operations. In anembodiment the noise is slowly changing, and the slowly changing noiseis selected from the group including AM radio and FM radio. In anembodiment the noise anticipated for each channel within group B is thelevel of cross-talk anticipated between two or more channelscommunicating at substantially the same time and in substantially thesame frequency. In an embodiment channels are allocated by anticipatedlevel of crosstalk in such a way as to maximize such cross-talk in orderto monitor it. In an embodiment channels in group B are repeatedlyturned on and off in such a manner that the amount of power-on time isreduced while still maintaining the monitoring of noise within the groupB channels. In an embodiment channels are defined according to one morechannels definers. In an embodiment the channel definers are selectedfrom the group comprising frequency, time slots, and codes. In anembodiment channels in groups A and B are repeatedly turned on and offin such a manner that the amount of power-on time is reduced while stillmaintaining the monitoring of noise within the group B channels. In anembodiment channels are defined according to one or more channelsdefiners. In an embodiment the channel definers are selected from thegroup comprising frequency, time slots, and codes.

In a further aspect the invention encompasses, in a communication systemthat includes multiple communication channels, operable in a low powermode, and operable in a high power mode, a method for storing controlparameters for use in high power mode. In an embodiment controlparameters are written into storage during high power mode. In anembodiment control parameters are stored in the storage during low powermode. In an embodiment control parameters are read from the storageduring low power mode. In an embodiment control parameters comprisephysical media dependent (PMD) parameters. In an embodiment controlparameters comprise a frequency value, an associated signal-to-noiseratio, an associated gain value an associated bit value. In anembodiment, for a plurality of frequencies, the associated gain valueand the associated bit value are stored, respectively. In an embodimentthe method comprises storing at least one pre-defined configured valuefor some channels, storing a pre-defined interpolation rule forapproximating power levels of communication channels in the system; andapproximating values of a high-power mode for the channels with storedconfigured values. In an embodiment the method comprises storingpre-defined times for switching from one power mode to another powermode, in particular for switching from the low power mode to the highpower mode. In an embodiment approximated values are stored that areassociated with frequencies for which otherwise no parameters are beingstored. In an embodiment all storage occurs in a memory storage unitassociated with a receiver in the communication system. An embodimentcomprises using the approximated values and the interpolation rule toapproximate the values of high power mode for the remaining channels. Anembodiment comprises communicating some of the approximated values fromthe PMD layer to one or more higher layers in the OSI model. Anembodiment comprises, after a system transition has begun from low powermode to a high power mode, comparing service value parameters of signalsreceived to the approximated service value parameters, adjusting powerlevels of channels to optimize service.

An embodiment further comprises, after a system transition has begunfrom low power mode to a high power mode, comparing service valueparameters of signals received to the approximated service valueparameters, adjusting power levels of channels to optimize service, andmodifying the interpolation rule to more accurately reflect the servicevalue parameters of signals received. An embodiment further comprises,after a system transition has begun from low power mode to a high powermode, comparing service value parameters of signals received to theapproximated service value parameters, adjusting power levels ofchannels to optimize service, and modifying the interpolation rule tomore accurately reflect the service value parameters of signalsreceived.

Those skilled in the art will recognize additional features andadvantages upon reading the following detailed description, and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments are herein described by way of example only; furtherexemplary embodiments are described below with reference to theaccompanying drawings. No attempt is made to show structural details ofthe embodiments in more detail than is necessary for a fundamentalunderstanding of the embodiments.

FIG. 1 illustrates one embodiment of a communication system including aserver-side transceiver and a client-side transceiver.

FIG. 2 illustrates one embodiment of a method for communicating within asystem that includes multiple communication channels, a low-power modeof operation, and at least one high power mode of operation.

FIGS. 3A, 3B and 3C (collectively referred to as FIG. 3) illustrate oneembodiment of a method for switching between multiple power modes in acommunication system such that the transmission power of one or moregroups of channels is reduced in at least one power mode.

FIG. 4 illustrates one embodiment of a method in a communication systemduring low-power mode, in which PMD control parameters are stored forlater use in a high power mode.

FIGS. 5A and 5B (collectively referred to as FIG. 5) illustrate oneembodiment of a flowchart of an exemplary process for switching from ahigh power operation to a low power operation.

FIG. 6 illustrates one embodiment of a flowchart of an exemplary processfor cyclically intermittent signal-to-noise measurement in low poweroperation.

FIGS. 7A and 7B (collectively referred to as FIG. 7) illustrate oneembodiment of a flowchart of an exemplary process for subcarrierinformation handling.

FIG. 8 illustrates one embodiment of a flowchart of an exemplary processfor subcarrier information estimation.

FIG. 9 illustrates one embodiment of a flowchart of an exemplary processused in subcarrier information estimation.

DETAILED DESCRIPTION

In this description, numerous specific details are set forth. However,the embodiments/cases of the invention may be practiced without some ofthese specific details. In other instances, well-known hardware,materials, structures and techniques have not been shown in detail inorder not to obscure the understanding of this description. In thisdescription, references to “one embodiment” and “one case” mean that thefeature being referred to may be included in at least oneembodiment/case of the invention. Moreover, separate references to “oneembodiment”, “some embodiments”, “one case”, or “some cases” in thisdescription do not necessarily refer to the same embodiment/case.Illustrated embodiments/cases are not mutually exclusive, unless sostated and except as will be readily apparent to those of ordinary skillin the art. Thus, the invention may include any variety of combinationsand/or integrations of the features of the embodiments/cases describedherein. Also herein, flow diagrams illustrate non-limitingembodiment/case examples of the methods, and block diagrams illustratenon-limiting embodiment/case examples of the devices. Some operations inthe flow diagrams may be described with reference to theembodiments/cases illustrated by the block diagrams. However, themethods of the flow diagrams could be performed by embodiments/cases ofthe invention other than those discussed with reference to the blockdiagrams, and embodiments/cases discussed with reference to the blockdiagrams could perform operations different from those discussed withreference to the flow diagrams. Moreover, although the flow diagrams maydepict serial operations, certain embodiments/cases could performcertain operations in parallel and/or in different orders from thosedepicted. Moreover, the use of repeated reference numerals and/orletters in the text and/or drawings is for the purpose of simplicity andclarity, and does not in itself dictate a relationship between thevarious embodiments/cases and/or configurations discussed. Furthermore,methods and mechanisms of the embodiments/ cases will sometimes bedescribed in singular form for clarity. However, some embodiments/casesmay include multiple iterations of a method or multiple instantiationsof a mechanism unless noted otherwise. For example, when a controller oran interface are disclosed in an embodiment/case, the scope of theembodiment/case is intended to also cover the use of multiplecontrollers or interfaces.

Certain features of the embodiments/cases, which may have been, forclarity, described in the context of separate embodiments/cases, mayalso be provided in various combinations in a single embodiment/case.Conversely, various features of the embodiments/cases, which may havebeen, for brevity, described in the context of a single embodiment/case,may also be provided separately or in any suitable sub-combination. Theembodiments/cases are not limited in their applications to the detailsof the order or sequence of steps of operation of methods, or to detailsof implementation of devices, set in the description, drawings, orexamples. In addition, individual blocks illustrated in the figures maybe functional in nature and do not necessarily correspond to discretehardware elements. While the methods disclosed herein have beendescribed and shown with reference to particular steps performed in aparticular order, it is understood that these steps may be combined,sub-divided, or reordered to form an equivalent method without departingfrom the teachings of the embodiments/cases. Accordingly, unlessspecifically indicated herein, the order and grouping of the steps isnot a limitation of the embodiments/cases. Embodiments/cases describedin conjunction with specific examples are presented by way of example,and not limitation. Moreover, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and scope ofthe appended claims and their equivalents.

Throughout this written description and the claims, the term “actualvalue” is the power level sufficient to overcome noise in a channel at aparticular time, typically but not exclusively, in a high power mode.Often this may be measured by SNR or SNRM. In some communicationsystems, “actual value” may include a parameter such as the level ofpower sufficient for communication of a certain number of bits per toneat a particular time.

Throughout this written description and the claims, the term“approximated value” is the power level value which is estimated to besufficient to overcome the existing noise on a channel when the channelswitches from low-power mode to a high power mode.

Through this written description and the claims, “bit loading” istransmission of information on a channel at a particular time. Bitloading requires that at least one bit of information be transmitted ata particular time. “Bit loading” is sometimes expressed by the phrase“communicating a bit of information”, and this latter phrase means thesame thing as “bit loading”.

Throughout this written description and the claims, the term“client-side” is the hardware and software owned by, or controlled by,or located at, the customer's site, also known as the “consumer's side”,or the “customer's premises”. The term “client side” is sometimesreferenced as “CPE”, which is short for “customer premises equipment”.In a cellular system or mobile system, the “client-side” would be themobile station.

Throughout this written description and the claims, the term “configuredvalue” is value of a received signal estimated prior to startup of thesystem, or prior to recalibration of the system, which is expected to beable to overcome the noise on the channel. “Configured value” might beequal at “actual value” for any particular time and on a particularchannel, but there may be a variance between a configured value and thecorresponding actual value.

Throughout this written description and claims, “interpolation rule” isa rule that takes the configured values of a sample of channels,compares the actual values of power levels received for such channels ata particular time, and uses the margin to determine approximated valuesfor the other channels in a system.

Throughout this written description and claims, the term “noisemonitoring” is sampling of background noise on a particular channel at aparticular time, unrelated to the transmission of information on thechannel. Noise monitoring is not the same as “bit loading”.

Throughout this written description and claims, “optimizing powerconsumption” means to reduce power consumption while maintaining acertain level of service, or to increase the level of service withoutsignificantly increasing power consumption. Similarly, “to optimizeservice” means to improve the service level of a system, oralternatively to achieve a desired level of service at a reduced levelof power consumption.

Throughout this written description and claims, the term “OSI model” isshort for “Open Systems Interconnection model”, and is a model ofcommunication between two units in a communication system in which eachunit in the system has the same number and kind of pre-defined layers,and the two units communicate at one or more pairs of the correspondinglayers. In the OSI model, the PMD layer is considered to be layer 1, andthere are six layers above layer 1. All embodiments discussed hereininvolve layer 1 to at least some degree, and some embodiments includeslayers other than layer 1.

Throughout this written description and the claims, the term “PMD” is anacronym for “physical medium dependent” layer, which is layer 1 in theseven-layer OSI model.

Throughout this written description and the claims, the term “powermode” is the various power levels active for the channels while thesystem is in a particular power mode. In the various embodimentspresented herein, there are at least two, and possibly more, powermodes. If there are exactly two power modes, then one will be the“low-power mode”, and the other will be the “full power mode”. If thereare three or more power modes, then one will be the “low-power mode”,and each of the other modes will be called a “higher-power mode”. It isunderstood that if there are two or more high power modes, each suchmode will have its own power allocation characteristics, which will bedifferent from the power allocation characteristics of the low-powermode.

Throughout this written description and the claims, the term “processingunit” is hardware, software, or a combination of both, which analyzesbits and bytes in a way similar to what a computer would do, in order totransform such bits and bytes into useful information. A processing unitmay be a CPU, an off-line processor, a combination of multipleprocessors performing parallel processing, or any similar kind of unitfor processing bits and bytes into information.

Throughout this written description and the claims, the term “serverside” is the hardware and software owned and controlled by the networkoperator. Also known as “operator side”, or “the network controlcenter”, or “the network operations center”, a “sever side” unit may bepart of the server-side transceiver, or may be at the server-side butnot physically part of the server-side transceiver.

Throughout this written description and the claims, the term “SNR” isshort for “Signal to Noise Ratio”, which is a measure of the power of acommunication signal on a channel relative to the noise on the channelat a particular point in time. “SNRM” is short for “Signal to NoiseMargin”, which measures the level by which the noise might rise untilcommunication is disrupted. SNR and SNRM are not the same, but they areboth measures of signal quality.

Throughout this written description and the claims, the term “storageunit” is hardware, software, or a combination of both, which storesinformation in the form of bits and bytes. A storage unit may be part ofa computer memory, RAM, ROM, off-line storage, FLASH memory, or anysimilar kind of unit for storing information.

FIG. 1 illustrates one embodiment of a communication system including aserver-side transceiver and a client side-transceiver, with acommunication link between the two transceivers. In FIG. 1, theserver-side is itself a system 105, which includes various components.One included component is a transceiver unit 110, which itself includesa transmitter 120, a receiver 125, and a controller 115 which managescommunication traffic into and out of the server-side system 105. Theserver-side system 105 also includes an implementation unit 130, whichallocates channels within the system to various groups, and whichallocates or does not allocate power to channels within the variousgroups. The server-side system 105 includes also a storage unit 135which is a memory unit that stores power values, data tables, and otherinformation required to implement various embodiments. The server-sidesystem 105 also includes a calculation unit 140 which uses pre-definedconfigured values and a pre-defined interpolation rule to calculateapproximated power values for various channels.

It will be understood that the particular configuration of componentsillustrated in FIG. 1 is only one of many configuration that may beimplemented as part of the server-side system 105. For example, there isshown a transceiver unit 110 with three components, but these componentsmay be configured separately from one another, or only the controller115 may be structured apart from the transceiver unit 110, or thetransmitter 1.20 and receiver 125 may be entirely separate with notransceiver unit 110. For example, any of the three components,implementation unit 130, storage unit 1.35, and calculation unit, may becombined with any one of the other three components, or all threecomponents may be combined in a single unit that performs all ofimplementation, storage, and calculation. For example, any of thecomponents depicted in the sever-side system 105 may be physicallystructured apart from other components in the server-side system 105, sothat there is a communication link between the separate component andthe rest of the server-side system 105. Many other alternativeembodiments are also possible, provided that some or all of thefunctions executed by the various components shown in FIG. 1 must beexecutable in an alternative embodiment.

There is a communication link 145 between the server-side system 105 anda client-side system 155. The nature of the communication link 145depends on the nature of the server-side 105 and client-side 1155systems. If the systems are DSL, then the link 145 will be a wireline,typically a telephone line, or perhaps a telephone line that is bundledwith other telephone lines. If the systems 105 and 155 are opticalsystems, the link 145 will likely be fiber optic line. If the systems105 and 155 are radio-based, meaning cellular, land mobile, satellite,or other wireless systems, there will not be a waveguide similar to awireline, and the link 145 will be a radio connection. Communicationlink 145 may be any kind of communication link that communicativelyconnects a server-side and a client-side.

The client-side system 155 contains the same or similar components asfound in the server-side system 105. One included component is atransceiver unit 160, which itself includes a transmitter 170, areceiver 175, and a controller 165 which manages communication trafficinto and out of the client-side system 155. The client-side system alsoincludes an implementation unit 180, which allocates channels within thesystem to various groups, and which allocates or does not allocate powerto channels within the various groups. The client-side system 155includes also a storage unit 185 which is a memory unit that storespower values, data tables, and other information required to implementvarious embodiments. The client-side system 155 also includes acalculation unit 190 which uses pre-defined configured values and apre-defined interpolation rule to calculate approximated power valuesfor various channels.

It will be understood that the particular configuration of componentsillustrated in FIG. 1 is only one of many configurations that may beimplemented as part of the client-side system 155. For example, there isshown a transceiver unit 160 with three components, but these componentsmay be configured separately from one another, or only the controller165 may be structured apart from the transceiver unit 160, or thetransmitter 170 and receiver 175 may be entirely separate with notransceiver unit 160. For example, any of the three components,implementation unit 180, storage unit 185, and calculation unit 190, maybe combined with any one of the other three components, or all threecomponents may be combined in a single unit that performs all ofimplementation, storage, and calculation. For example, any of thecomponents depicted in the client-side system 155 may be structuredapart from the system 155 itself, so that there is a communication linkbetween the separate component and the rest of the system 155. Manyother alternative embodiments are also possible, provided that some orall of the functions executed by the various components shown in FIG. 1must be executable in an alternative embodiment.

FIG. 2 illustrates one embodiment of a method for communicating within asystem that includes multiple communication channels, a low-power modeof operation, and at least one high power mode of operation. At start205, the system pre-defines multiple communication channels, a low-powermode of operation, and at least one higher-power mode of operation. In210, channels are allocated into at least two groups, although there maybe three or more groups as well. Some embodiments will include onlyGroup A 215 and Group B 220, in which Group A 215 is channels which donot communicate bits of information in low power mode and which did notcommunicate bits of information in the previous higher-power mode ofoperation, while group B 225 is channels which do not communicate bitsin low power mode and which did communicate bits of information in theprevious higher-power mode. In other embodiments, there will be a GroupA 215 as defined above, and a Group C 225 which is channels whichcommunicate bits of information in low power mode. Many other kinds ofchannel groups are possible, as shown in Group D 230. For example, GroupD 230 may be channels which have been defined as mission-critical forthe system, and which remain on a pre-determined power at all times.Other criteria for Group D 230 are also possible. In addition to havingany two groupings of channels from Groups A 215, B 220, C 225 and D 230,respectively, there may be a grouping with any of three groups, such as,solely as one example, Groups A 215, B 220, and C 225. A grouping withall four groups is also possible. Other configurations, involving morethan four groupings of channels, are also possible, provided that thechannel groups are defined in such a way that every channel is placedinto one group. In some embodiments, one of the groups of channels maybe turned on and off, in which “on” means that the power allocationduring that period will be as pre-defined in the system, and the “off”means that no power is allocated to channels in that group during theoff-period. One example, shown in FIG. 2, is on and off 235 for Group B220.

FIGS. 3A and 3B illustrate one embodiment of a method for switchingbetween multiple power modes in a communication system such that thetransmission power of one or more groups of channels is reduced in atleast one power mode. The embodiment presented in FIG. 3C presents anexample in which channel groups are turned on and off.

In FIG. 3A, in Mode X 310, all of the channels in Group A, Group B, andGroup D, are turned off. However, Group C channels are turned on, inwhich channel C1 is defined at a certain power level, while channel C2is defined at a different, higher power level A “channel” is defined bya channel definer, which may be one of several factors. In an FDMsystem, the channel definer will be the frequency of the channel. In aTDM system, the channel definer will be the time slot of the channel. Ina CDM system, the channel definer will be the code for that channel.Also, a channel may be defined by any combination of frequency, timeslot, and code.

In FIG. 3B, in Mode Y 320, the power level configuration has changed.Group A channels are still turned off. However, the channels in Group Band Group D, which were formerly turned off in Mode X 310, are nowturned on in Mode Y 320, in which channel B1 has been allocated a higherpower level than channel B2, and channel D1 has been allocated a lowerpower level than channel D2. The channels in Group C are still on inMode Y 320. In the example shown in FIG. 3B, channel C 1 is still at alower power level than channel C2, which will be the case in someembodiments, but in other embodiments, this may be changed, perhaps dueto changes in noise levels, and channel C1 may have a higher powerallocation than does channel C2.

In FIG. 3C, there is a switching 330 between Mode X 310 and Mode Y 320,over time. In the particular example shown in FIG. 3C, the time slotsfor each of Mode X 310 and Mode Y 320 are equal, and the length of thetime slot does not change. This, however, is only one embodiment ofswitching 330 between Mode X 310 and Mode Y 320. In other embodiments ofthe switching 330, the time slots for Mode X 310 will be of differentduration than the time slots for Mode Y 320. In other embodiments of theswitching 330, the modes will not be of fixed time-length, but mayrather vary, for example, in accordance with pre-defined PMD timedurations which, for example, are stored at both the server-side system105 and the client-side system 155.

A first embodiment is a method for communicating within a communicationsystem that includes multiple communication channels, a low power modeof operation, and at least one higher-power mode of operation. Thesystem allocates each channel to one of at least two groups, in whichgroup A is channels which do not communicate bits of information in lowpower mode and which did not communicate bits of information in theprevious higher-power mode of operation, and group B is channels whichdo not communicate bits in low power mode and which did communicate bitsof information in the previous higher-power mode. The system does notallocate any power, during low power mode, to the channels in Group A.During low power mode, the system allocates sufficient power to eachchannel in Group B so that a resulting SNR shall be sufficient for thesystem to monitor the noise in that channel. In this embodiment, thesteps described are implemented in an implementation unit that may belocated in either the server-side system 105 or the client-side system155. If at the server-side 105, then the server-side implementation unit130 implements the steps. If at the client-side 155, then theclient-side implementation unit 190 implements the steps.

A second embodiment is a method for communicating within a communicationsystem that includes multiple communication channels, a low power modeof operation, and at least one higher-power mode of operation. Thesystem allocates each channel to one of at least two groups, in whichgroup A is channels which do not communicate bits of information in lowpower mode and which did not communicate bits of information in theprevious higher-power mode of operation, and group C is channels whichcommunicate bits of information in low power mode. The system does notallocate any power, during low power mode, to the channels in Group A.During low power mode, the system allocates sufficient power to eachchannel in Group C that a resulting SNR for that channel shall besufficient for the system to load at least one bit per time slot ontothat channel. In this embodiment, the steps described are implemented inan implementation unit that may be located in either the server-sidesystem 105 or the client-side system 155. If at the server-side 105,then the server-side implementation unit 130 implements the steps. If atthe client-side 155, then the client-side implementation unit 190implements the steps.

In an alternative embodiment to the first embodiment described above,the method also includes the system allocating channels to a thirdgroup, Group C, which includes channels that communicate bits ofinformation in low power mode. Further, the system also allocatessufficient power to each channel in Group C, during low power mode, sothat a resulting SNR shall be sufficient for the system to load at leastone bit per time slot onto that channel.

In a possible configuration of the alternative embodiment justdescribed, the channels in Group B are further allocated into subgroupson the basis of a criterion.

In a first possible variation of the configuration just described, thecriterion for sub-grouping of the channels in Group B is the duration oftime of transmission for each channel.

In a second possible variation of the configuration just describedabove, the criterion for sub-grouping of channels in group B is randomallocation such that no channel in Group B is correlated with any otherchannel in Group B.

In a third possible variation of the configuration just described above,the criterion for sub-grouping of channels in group B is the kind ofnoise anticipated for each such channel within Group B.

In a first possible option of the third possible variation justdescribed, the noise anticipated for the channels within Group B iseither quickly changing noise or slowly changing noise.

In a first possible format for the first possible option just described,the noise is quickly changing, and the quickly changing noise isselected from the group including ham or other amateur radio operations,police radio operations, and land mobile operations.

In a second possible format for the first possible option justdescribed, the noise is slowly changing noise, and the slowly changingnoise is selected from the group including AM radio and FM radio.

In a second possible option of the third possible variation describedabove, the noise anticipated for each channel within Group B is thelevel of cross-talk anticipated between two or more channelscommunicating at substantially the same time, in substantially the samefrequency, and, if they are used, with substantially the same codes.

In a possible format of the second possible option just described, thechannels are allocated by anticipated level of crosstalk in such a wayas to maximize such cross-talk. This is done in order to monitor thepossible maximum level of cross-talk between channels.

In a fourth possible variation of the configuration described above, thechannels in Group B are repeatedly turned on and off in such a mannerthat the amount of power-on time is reduced while still maintaining themonitoring of noise within the group B channels.

In a possible option for the fourth possible variation just described,the channels are defined according to one more channels definers.

In a possible format of the possible option just described, the channeldefiners are selected from the group comprising frequency, time slots,codes, or some combination of the foregoing.

In a fifth possible variation of the configuration described above, thechannels in Groups A and B are repeatedly turned on and off in such amanner that the amount of power-on time is reduced while stillmaintaining the monitoring of noise within the group B channels.

In a possible option for the fifth possible variation just described,the channels are defined according to one more channels definers.

In one possible format for the possible option just described, thechannel definers are selected from the group comprising frequency, timeslots, codes, or some combination of the foregoing.

In FIG. 4, there is a communication system that has multiple channels, alow power mode, and a higher-power mode. FIG. 4 illustrates oneembodiment of a method for storing, during a low power mode, PMD controlparameters to be applied in a higher-power mode. In 410, the system haspre-stored configured values for some of the channels. In 420, thesystem has pre-stored an interpolation rule for determining approximatedpower values for channels in the system. In 430, the system haspre-stored PMD dines for switching between a low power mode and ahigher-power mode. It will be understood that all of this information,being configured values for some of the channels, an interpolation rule,and PMD switching times, will be stored prior to other steps in themethod illustrated. In the example illustrated, the order of storing isconfigured values 410, then interpolation rule 420, then PMD switchingtimes 430, but it is understood that any of these three pieces ofinformation may be stored first, any may be stored second, and any manybe stored third, provided that all three are pre-stored prior toadditional steps in the method. In 440, the system approximates powervalues of channels in the system for the next higher-power mode. In 450,the system stores the approximated power values.

In some embodiments, the steps are executed at the server-side system105, in which storage occurs in the server-side storage unit 135, andapproximating values occurs in the server-side calculation unit 140. Insuch embodiments, upon switch from low power mode to higher-power mode,the server-side receiver 125 will receive transmissions from theclient-side transmitter 170, via the communication link 145, and theserver-side system 105 will calculate and transmit power adjustments onthe basis of the SNR of the signals received.

In some embodiments, the steps are executed at the client-side system155, in which storage occurs in the server-side storage unit 185, andapproximating values occurs in the server-side calculation unit 190. Insuch embodiments, upon switch from low power mode to higher-power mode,the client-side receiver 175 will receive transmissions from theserver-side transmitter 120, via the communication link 145, and theclient-side system 155 will calculate and transmit power adjustments onthe basis of the SNR of the signals received.

In one embodiment, there is a communication system that includesmultiple communication channels, a low power mode of operation, and atleast one higher-power mode of operation. The system executes a methodfor storing, during low power mode, PMD control parameters for ahigher-power mode. In particular, the system stores pre-definedconfigured values for some channels in the systems, a pre-definedinterpolation rule approximating power levels of communication channelsin the system during a higher-power mode, and pre-defined PMD times forswitching from one power mode to another power mode. During a low powermode, the system approximates values at a higher-power mode for channelswith stored configured values. The system then stores these approximatedvalues. This embodiment is executed at either the server-side system 105or the client-side system 155. If at the server-side system 105, thenthe server-side calculation unit 140 approximates the values, and theserver-side storage unit 135 stores the approximated values. If at theclient-side system 155, then the server-side calculation unit 190approximates the values, and the server-side storage unit 185 stores theapproximated values.

In a first alternative embodiment of the embodiment just described, thesystem further uses the approximated values and the interpolation ruleto approximate the values of a higher-power mode for the remainingchannels.

In a second alternative embodiment of the embodiment just described, thesystem communicates some of the approximated values from the PMD layerto one or more higher layers in the OSI model. In such a system, thecommunication to the higher layers occurs in both the server-side system105 and client-side system 155.

In a third alternative embodiment of the embodiment just described,further after a system switch has begun from low power mode tohigher-power mode, a receiver in the system compares service valueparameters of signals received to the approximated service valueparameters. If the receiver is the server-side receiver 125, then theserver-side system 105 also calculates adjusted power levels of channelsto optimize service, and modifies the interpolation rule to moreaccurately reflect the service value parameters of signals received. Ifthe receiver is the client-side receiver 175, then the client-sidesystem 155 also calculates adjusted power levels of channels to optimizeservice, and modifies the interpolation rule to more accurately reflectthe service value parameters of signals received.

In a possible configuration of the first alternative embodiment justdescribed, further after a system switch has begun from low power modeto higher-power mode, a receiver in the system compares service valueparameters of signals received to the approximated service valueparameters. If the receiver is the server-side receiver 125, then theserver-side system 105 also calculates adjusted power levels of channelsto optimize service, and modifies the interpolation rule to moreaccurately reflect the service value parameters of signals received. Ifthe receiver is the client-side receiver 175, then the client-sidesystem 155 also calculates adjusted power levels of channels to optimizeservice, and modifies the interpolation rule to more accurately reflectthe service value parameters of signals received.

In a possible configuration of the second alternative embodiment justdescribed, further after a system switch has begun from low power modeto higher-power mode, a receiver in the system compares service valueparameters of signals received to the approximated service valueparameters. If the receiver is the server-side receiver 125, then theserver-side system 105 also calculates adjusted power levels of channelsto optimize service, and modifies the interpolation rule to moreaccurately reflect the service value parameters of signals received. Ifthe receiver is the client-side receiver 175, then the client-sidesystem 155 also calculates adjusted power levels of channels to optimizeservice, and modifies the interpolation rule to more accurately reflectthe service value parameters of signals received.

An exemplary embodiment of a method or process for switching from a highpower operation to a low power operation is described below withreference to FIG. 5. At 505, the client-side system 155 recognizes thattraffic conditions are fulfilled for transition from a high poweroperation, in particular from a full power operation, to a low poweroperation. At 510, a subcarrier index variable i is set to zero (i=0).At 515 the subcarrier index variable i is incremented by one (i=i+1). At520, a check is performed to see, if subcarrier i is not used for bitloading in the high power mode of operation and if subcarrier i shallnot be used for bit loading in the low power mode of operation as well.If subcarrier i neither is used for bit loading in the high power modeof operation nor shall be used for bit loading in the low power mode ofoperation, then, at 525, subcarrier i is determined to belong to and/orassigned to a class A of subcarriers whose power in the low power modeof operation of subcarrier i shall be zero (power off) or at leastreduced. Then, at 530, it is checked if i equals the “last” index, inparticular, the largest index used for subcarriers. If so, at 535, thelow power mode of operation is to be entered and from 535 the method iscontinued at 540. Otherwise the method is continued at 515.

If at 520 at least one of the following was found (i) subcarrier i isused in the high power mode of operation for bit loading and (ii)subcarrier i shall be used for bit loading in the low power mode ofoperation, then, at 570, it is checked if subcarrier i is used for hitloading in the high power mode of operation but shall not be used forbit loading in the low power mode of operation. If so, then, at 575, itis determined that subcarrier i belongs to the class B of subcarrierswhose power in the low power mode of operation shall be minimized underthe constraint that the resulting signal-to-noise ratio (SNR) is stillsufficient for noise monitoring. Then the method is continued at 530 asdescribed above.

If at 570 it was not found that (i) subcarrier i is used for bit loadingin the high power mode of operation and (ii) subcarrier i shall not beused for bit loading in the low power mode of operation, then, at 580,it is checked if subcarrier i shall be used for bit loading in the lowpower mode of operation. If not, the method is continued at 530 asdescribed above. However, if so, at 585, it is determined thatsubcarrier belongs to the class C of subcarriers whose power in thelow-power mode of operation shall be minimized under the constraint thatthe resulting SNR is still sufficient for loading at least one bit. Thenthe method is continued at 530 as described above.

At 540, it is checked, if additional power savings should be made in thelow power mode of operation by dynamically switching subcarriers on andoff. If not, at 545, the low power mode of operation is enteredaccordingly. If at 540 it was determined that additional power savingsshould be made in the low power mode of operation by dynamicallyswitching subcarriers on and off, then, at 550, it is checked, if allsubcarriers which do not belong to the class C of subcarriers should beswitched on and off. If not, at 555, it is determined for subcarriersthat belong to class B that these subcarriers should be switched on andoff in a cyclic fashion during the lower power mode of operation. Then,at 545, the low power mode of operation is entered. However, if at 550it was found that all subcarriers which do not belong to the class C ofsubcarriers should be switched on and off, then at 560, it is determinedfor all subcarriers that do not belong to class C that these subcarriersshould be switched on and off in a cyclic fashion during the lower powermode of operation. Then, at 545, the low power mode of operation isentered.

An exemplary embodiment of a method or process for cyclicallyintermittent signal-to-noise measurement in low power operation isdescribed below with reference to FIG. 6. At 605, the low power mode ofoperation is entered wherein the low power mode of operation realizesadditional power savings by dynamic suhcarrier on/off-switching forsubcarriers numbered k=1 to k=K and/or in a cyclic fashion with a cyclenumbered from data symbol s=1 to s=S. At 610, a cycle number variable sis set to zero (s=0). At 615 the cycle number variable s is incrementedby one (s=s+1). At 620, it is checked if a data symbol at cycle number sis in the low power mode of operation rather than in a high power modeof operation. If not, then at 625 an exit is made from the low powermode of operation. Otherwise, at 630, a subcarrier index variable k isset to zero (k=0). At 635, the suhcarrier index variable k isincremented by one (k=k+1). At 640, it is checked if the suhcarrier withthe index k has a power-off assignment at a cycle with cycle number s(in short: cycle s). If so, at 650, power for suhcarrier k is switchedof in cycle s and the process moves on to the next process step at 645.Otherwise the process moves directly from the checking at 640 to thenext process step at 645. At 645, it is checked if k equals the number Kof subcarriers. If not, the process moves on to step 635. Otherwise, at655, it is checked if it is permitted to change a step size in theinverse Fourier transformation. If not, the process moves on to a stepat 660, where it is checked if s equals S. If so the process moves on to610, otherwise the process moves on to 615. If, at 655, it is determinedthat it is permitted to change a step size in the inverse Fouriertransformation, then, at 665, it is checked if the step size in theinverse Fourier transformation can be reduced. If not, the process moveson to the step at 660. Otherwise, first the step size in the inverseFourier transformation is reduced, and then the process moves on to thestep at 660. The afore-described exemplary embodiment is used in atransmit portion. A corresponding embodiment can be used in a receiveportion, wherein, instead of the inverse Fourier transformation, aFourier transformation is performed.

An exemplary embodiment of a method or process for subcarrierinformation handling is described below with reference to FIGS. 7A and7B. At 705, a channel operation (L0) is performed with high power. Thebit gain table for L0 channel operation (BGT(L0)) is used which containsper subcarrier information about the number of loaded bits and the gain.At 710, traffic conditions are recognized to be fulfilled for transitionfrom the high power mode of operation (L0) to a low power mode ofoperation (L2). At 715, an approximation BGAT(L0) of values in BGT(L0)is determined. The approximation can be represented via a set ofbits/gains breakpoints and interpolation in between. The approximationuses a margin between actual and configured minimum service parametervalues. At 720, a set of determined bits/gains breakpoints iscommunicated to a far-end transceiver. At 725, before the transition tothe low power mode of operation, it is checked, if BGAT(L0) shall beapplied. If not, at 735, upper layers are informed, if the actual datarate is smaller due to the approximation (or not), otherwise first, at730, the change is applied in a synchronized fashion between near-endtransceiver and far-end transceiver from BGT(L0) and BGAT(L0), beforethen moving on to the step at 735. Then, at 740, the synchronizedtransition between near-end transceiver and far-end transceiver from thefull power mode of operation to the low power mode of operation isapplied with BGT(L2). At 745, the set of bits/gains breakpoints or theentire table BGAT(L0) is stored during the low power mode of operation.At 750, traffic conditions are recognized to require a transition fromthe low power mode of operation to the high power mode of operation. At755, if only the set of bits/gains breakpoints are stored during the lowpower triode of operation, the change from BGT(L2) to BGAT(L0) withbreakpoints derived from BGAT(L0) is applied in a fashion synchronizedbetween near-end transceiver and far-end transceiver. At 760, afterre-entering the high power mode of operation, for obtaining the channeloptimization as in the previous high power mode of operation,synchronized online reconfigurations between near-end transceiver andfar-end transceiver are applied. At 765, the channel optimized highpower mode of operation is performed.

An exemplary embodiment of a method or process for subcarrierinformation estimation is described below with reference to FIG. 8. At805, an approximation BGAT(L0) of BGT(L0) is started. The approximationBGAT(L0) can be represented via a set of bits/gains breakpoints andinterpolation. At 810, a receiver's minimum required signal-to-noiseratio SNRTHR(b) is determined for loading of b bits with b=0, 1, 2 . . .b_max. A special value for b=0 can be SNRTHR(b=0) SNRTHR(b=1)−3 dB. At815, an approximated and/or averaged SNR(i) graph is created. Under theassumption that a fine gain value is identical for all subcarriers, anidealized graph with linear slope between two points where an SNRTHRvalue is crossed can be used. At 820, a subcarrier index of thebits/gains breakpoints can be determined such that the first subcarrierwith bit loading is the first breakpoint, the last subcarrier with bitloading is the last breakpoint and each subcarrier near by the locationwhere the idealized SNR graph crosses an SNRTHR value can be abreakpoint. At 825, the bits/gains values of the bits/gains breakpointderived from the idealized SNR graph and SNRTHR values are determinedsuch that the service constraints in terms of rate and minimum SNRmargin are fulfilled. At 830, a set of bits breakpoints with bits valueand subcarrier index value and a set of gains breakpoints with gainsvalue and subcarrier index value are provided.

An exemplary embodiment of a process used in subcarrier informationestimation is described below with reference to FIG. 9. At 905, are-calculation of BGAT(L0) is started from the set of bits/gainsbreakpoints and an interpolation is performed. At 910, it is checked, ifthe interpolation should be strictly linearly. If so, at 925, BGAT(L0)values for subcarriers between two breakpoints are derived for eachsubcarrier by linear interpolation. Then, at 920, the re-calculatedBGAT(L0) consists of the bits/gains breakpoints values plus theinterpolated values. If, at 910, the interpolation is determined not tobe strictly linear, then at 915, BGAT(L0) for subcarriers between twobreakpoints are derived such that the value adder for each of thesesubcarriers is constant. In an example, two gains breakpoints areg(1)=[i(1)]and g(1+1)=[i(1+1), g(1+1)]. A value g_grid defines asmallest gain resolution; in an example, g_grid= 1/256 dB. A valueg_value_adder=ceil((g(1+1)−g(1))/(i(1+1)−i(1))/g_grid)*g_grid is used ina loop to calculate a gain value for a respective index i: for i=i(1)+1,i(1+1)−1; g_value_adder; end.

Terms such as “first”, “second”, and the like, are used to describevarious elements, regions, sections, etc. and are not intended to belimiting. Like terms refer to like elements throughout the description.

As used herein, the terms “having”, “containing”, “including”,“comprising” and the like are open ended terms that indicate thepresence of stated elements or features, but do not preclude additionalelements or features. The articles “a”, “an” and “the” are intended toinclude the plural as well as the singular, unless the context clearlyindicates otherwise.

With the above range of variations and applications in mind, it shouldbe understood that the present invention is not limited by the foregoingdescription, nor is it limited by the accompanying drawings. Instead,the present invention is limited only by the following claims and theirlegal equivalents.

1-20. (canceled)
 21. An apparatus for use in a communications systemhaving a plurality of communication frequency channels operable tocommunicate bits of information bits in a higher power mode of operationand operable to communicate the information bits in a lower power modeof operation, the apparatus comprising: circuitry configured, for thelower power mode of operation, to allocate power to a channel of theplurality of communication frequency channels based on use of thatchannel during the higher power mode of operation, and in the lowerpower mode, to allocate the power to the channel by setting the power ofthe channel to a minimum that provides a noise monitorable channel,wherein in the higher power mode of operation the channel includesinformation bits and in the lower power mode the channel does notinclude information bits.
 22. The apparatus of claim 21, wherein in thelower power mode a bit loading is set to zero such that the channel doesnot include information bits.
 23. The apparatus of claim 21, wherein inthe lower power mode the power is sufficient to generate asignal-to-noise ratio (SNR) to allow monitoring of noise on the channel.24. The apparatus of claim 21, wherein in the circuitry is arranged on aserver side.
 25. The apparatus of claim 21, wherein in the powerallocated is based on corrective information indicating received powerlevels.
 26. The apparatus of claim 21, wherein the power to the channelis cyclically changed to minimize the power of the channel that allowsthe frequency channel to be monitored.
 27. The apparatus of claim 21,wherein the power of at least two respective channels is minimized inthe low power mode to form a group, the circuitry further beingconfigured to allocate the power to one channel in the group at a time.28. The apparatus of claim 21, wherein the circuitry is furtherconfigured to perform a measurement of a signal-to-noise ratio todetermine whether the channel can be monitored.
 29. The apparatus ofclaim 28, wherein the measurement is performed using a Fouriertransformation, wherein a number of frequencies used in the Fouriertransformation varies with a maximum frequency used for thesignal-to-noise ratio measurement in the plurality of communicationchannels.
 30. The apparatus of claim 29, wherein the number offrequencies used in the Fourier transformation varies proportionally tothe maximum frequency used for the signal-to-noise ratio measurement inthe plurality of communication frequency channels.
 31. A method for acommunications system having a plurality of communication frequencychannels operable to communicate information bits in a higher power modeof operation and operable to communicate information bits in a lowerpower mode of operation, the method comprising: in the lower power modeof operation, allocating power to a channel of the plurality ofcommunication frequency channels based on use of that channel during thehigher power mode of operation, and in the lower power mode, allocatingthe power to the channel by setting the power of the channel to aminimum that provides a noise monitorable channel, wherein in the higherpower mode of operation the channel includes information bits and in thelower power mode the channel does not include information bits.
 32. Theapparatus of claim 31, wherein in the lower power mode a bit loading isset to zero such that the channel does not include information bits. 33.The method of claim 31, wherein in the lower power mode the power issufficient to generate a signal-to-noise ratio (SNR) to allow monitoringof noise on the channel.
 34. The method of claim 31, wherein in thepower allocated is based on corrective information indicating receivedpower levels.
 35. The method of claim 31, wherein the power to thechannel is cyclically changed to minimize the power of the channel thatallows the frequency channel to be monitored.
 36. The method of claim31, further comprising performing a measurement of a signal-to-noiseratio to determine whether the channel can be monitored.
 37. The methodof claim 36, wherein performing the measurement is performed using aFourier transformation, wherein a number of frequencies used in theFourier transformation varies with a maximum frequency used for thesignal-to-noise ratio measurement in the plurality of communicationchannels.
 38. The method of claim 37, wherein the number of frequenciesused in the Fourier transformation varies proportionally to the maximumfrequency used for the signal-to-noise ratio measurement in theplurality of communication frequency channels.
 39. An apparatus for usein a communications system having a plurality of communication frequencychannels operable to communicate information bits in a higher power modeof operation and operable to communicate information bits in a lowerpower mode of operation, the apparatus comprising: circuitry configured,for the lower power mode of operation, to receive signals with anallocated power over a channel of the plurality of communicationfrequency channels based on use of that channel during the higher powermode of operation, and in the lower power mode, receive signal with anallocated power of a channel set the power of the channel to a minimumthat provides a noise monitorable channel, wherein in the higher powermode of operation the channel includes information bits and in the lowerpower mode the channel does not include information bits.
 40. Theapparatus of claim 39, wherein in the lower power mode a bit loading isset to zero such that the channel does not include information bits. 41.The apparatus of claim 39, wherein in the lower power mode the power issufficient to generate a signal-to-noise ratio (SNR) to allow monitoringof noise on the channel.
 42. The apparatus of claim 39, wherein in thecircuitry is arranged on a server side.
 43. The apparatus of claim 39,wherein in the power allocated is based on corrective informationindicating received power levels.
 44. The apparatus of claim 39, whereinthe power to the channel is cyclically changed to minimize the power ofthe channel that allows the frequency channel to be monitored.